DE2137842A1 - DEVICE FOR MEASURING THE REFRACTORY INDIVIDUALITY OF LIQUIDS OR GASES, IN PARTICULAR FOR DETERMINING THE MIXING RATIO OF SEVERAL COMPONENTS OF SUCH LIQUIDS OR GASES - Google Patents

Description

Equipment for measuring the refractive index of liquids or gases, especially for determining the mixing ratio of several components of such Liquids or gases.

The invention relates to devices for measuring the refractive index of Liquids or Gesen as well as bodies, which the dependence of the refractive index of certain physical quantities to measure these physical quantities use.

Well-known institutions of this type are essentially designed in such a way that that a certain beam path is examined through the material of interest and is measured geo @ strically precisely.

A disadvantage of the known measuring devices is that a defined Light beam must be generated and that the @@@ light beam just @ o like the interfaces or surfaces of the substance to be examined exactly on each other need to be aligned when a reasonably reproducible measurement is performed shall be. The surfaces of the body to be examined with regard to its refractive index must by no means have any medium shape here. except @ radiation sources / special aids must be shielded to prevent falsification of the measurement result to avoid The invention aims to solve the problem the refractive index of liquids or gases without the study of a geometric To be able to @ hmen the beam path. About the determination of the refractive index should also the mixing ratios of liquid or gas mixtures can be determined can.

This object is achieved according to the invention in that a source of radiation and a fot @@ sensitive organ jewe @ is with S @@@ surface area of a Lich @@@ ters gekoppe @@ are, de @ich to @@@ end face areas then @@@@@ fläne @@@@ lle aufwel @@@.

with steadily decreasing curvature range @@ us into a dimension @@ surface area of the light guide without the measuring point surface area Radius of curvature becomes @@ (edge or point) and that Ph @@@ engrenze in @@@@@@@ len surface covers a substance with the @@ determining @ @ r @@ number and a substance with constant or be @ annter Bre @ hzah @ au @@@ - other borders.

It was found that the surface shape described in this way a light guide can be achieved that a very small measuring point surface area @ i @ h to di @@ em fiber optics for the transmission of the light from the radiation source to the photo-receptive organ is decisive, while the conditions of the rest Surface parts of the light guide have a relatively low influence on the light transmission to have. It @@ t therefore possible by changing the conditions for the dead reflection a corresponding, Measured value-dependent modulation of the light flux arriving at the photosensitive organ to achieve without d @ ß the measurement result of the conditions outside @es the measuring point surface area can be falsified.

@ i @ W @@@ ntlicher Vorteil de @ Training of the at the Meßstell @@@ @b @@ äch @ nb @ richly adjoining surface parts of the light @@@@@@@@ @@ zur Me @ stelie towards steadily @@@ in a growing curvature @@@@@ radius @ @@, @ e @ @@@ @@@ the entire, @@@@@@ leit @ t @@ luminous flux a maximum luminous flux over the measuring point can be directed to the photo-sensitive organ and can be used for the measurement. The result is an extremely sensitive and reliable one Measuring device.

If the light guide is a curved light guide rod, which at one end with a radiation source and at the other end with the photo-sensitive Organ nskonnalt is such a chain line.

can be the bend according to a hyperbola, / a parabola or a Ellipse half be selected, with the measuring point surface area in the vertex 0 According to another, advantageous design, the light guide has at least in sections the shape of a body of revolution, for example accordingly the part of a hyperboloid, paraboloid, or ellipsoid, again being the vertex this body forms the measuring point and both radiation source and fotoemp Sensitive organ arranged on an opposite end face of this body are.

However, the invention also includes embodiments, both of the light guides a cavity filled with the substance to be examined, the one previously described Shape or profiling is.

As is well known, the refractive index of a mixture of several components depends on the respective mixing ratio, can be obtained from the refractive index measurement result for systems consisting of two mixture components, the mixing ratio is calculated directly or be derived.

Because of the different wavelength dependence of the refractive indices The mixing ratios of mixtures of substances can also be determined with devices according to the invention Determine in mixtures of three components by alternately or simultaneously Measurements with respect to radiation of different wavelengths can be performed. Finally, it should be noted that because of the Temperature dependence the refractive index the devices according to the invention are suitable simultaneously for or instead of specifying a mixing ratio, also a temperature value to be able to specify or derive.

Appropriate refinements of the invention also form the subject matter of the attached claims.

The invention is illustrated below with the aid of a number of examples of ads explained in more detail with reference to the accompanying drawings .. They show: Figure 1 is a schematic, partially in section drawn side view of the front Part of a light guide of a device according to the invention to explain the Basic concept, Figure 2 is a schematic, perspective view of an embodiment fer invention, Figures 2a and 2b are schematic illustrations of various embodiments of the light guide for a Einriehtung according to the invention according to Figure 2, Figure 3 is a perspective, schematic view of another embodiment of the invention; Figures 3a and 3b are schematic illustrations of other shapes of the light guide for a Device according to Figure 3, Figure 4 is a perspective, schematic illustration yet another embodiment of the winding, Figure 5 is a perspective, schematic illustration of yet another embodiment of the invention, figure 6 shows a three-dimensional graphic representation to explain the mode of operation a combination for determining the mixing ratios of mixtures of substances three components, Figure 7 is a greatly simplified representation of a device to determine the mixing ratio and / or the temperature of a mixture of substances, Figure 8 is a graphical representation of the meter display of the facility according to Figure 7 and Figures 9 to 12 further embodiments of the invention accordingly Figure 7.

Looking at the part of an ellipsoid shown in FIG corresponding light guide body 1 a bundle of rays which is parallel to the axis 2 is directed downwards, it can be determined that those rays running close to axis 2 when they first hit the phase boundary 3 leave the Liohtleiterköper 1 5 bai change the angle a with respect to the normal to the tangential surface T falls below the critical angle of total reflection, all below at a smaller angle to the tangential plane on the surface 3 of the Sorper @ i, at a greater distance from the axis 2 who experience running rays first of all a first total reflection within the light guide body 1, but they remain on the subsequent impact of iflncn against the surface of the light guide body 1 again only in this, even if now the critical size of the angle a is not fallen below.

It has now been shown that a most favorable ratio of total introduced radiation corresponding to the value R to the fully reflected and radiation returned in the direction of the axis corresponding to the value r is achieved when the surface 3 of the light guide body 1 is steadily smaller becoming Radius of curvature merges into the vertex without here a point or edge is formed. The considerations made apply of course not only for ellipsoid-like, hyperboloid-like or parabollod-like bodies of revolution, but also for flat, disk-like conductor bodies, which can be seen in a side view show a shape corresponding to the figure i or for light guide rods that curved according to a conical curve or a Keti @ nlinis or the like are, which will be discussed in connection with the drawing figures 2, @@ and 2b will. In any case, di @@@ n F @ rmen the light guide body gem @ insam that for the Refl @@ ion one in the direction @@@ brought in the vertex of the light guide body Stra @ l @ ng the conditions at the phase boundary between the light conductor body and the environment in a narrowly limited measuring point surfaces @@@@ you 4 are crucial, since all norma @@@@@ eise back to the radiation-sensitive organ gelqi @@@ en light rays experience here at least once an inner total reflection when this total reflection not by consciously influencing the conditions at the phase boundary in dies @@ Area is prevented.

In the embodiment of Figure 2, the light guide body 1 has the Shape of a light guide rod bent according to a parabolic part, with which at one end a radiation source 5 and at the other end a radiation-sensitive one Grgan 6 are coupled. The radiation-sensitive organ 6, for example, is one Photocell is connected to a measuring device 7. A amplifier can use the measuring device be connected upstream or located in the measuring device.

Below the light guide body 1 there is a container 8 in which a liquid to be examined is admitted via a pipe 9 can. The liquid wets the measuring point surface area 4 of the light guide body 1 and @@ have the effect that the deflection of the measuring device 7 depends on the refractive index the liquid in the container 8 or because of of addiction the refractive index of these values depends on the temperature or the mixing ratio changed, whereby in each case a corresponding calibration of the measuring device 7 is taken can be.

Instead of the parabolic shape, the light guide body 1 can accordingly a hyperload or curved halfway an ellipse, like the Figures 2a and 2b can be seen in the drawing.

The container 8 of the embodiment according to FIG. 2 can also contain the measuring point surface area 4 of the light guide body i umsohließen in such a way that the arrangement for examination gaseous or vaporous substances is suitable. For this purpose, the Bei container 8 be provided with corresponding connections 10 and 11, as shown schematically shown in the embodiment according to FIG. 3 Here, however, the light guide body has in contrast to the embodiment according to FIG. 2, the shape of an ellipsoid of revolution 12, whose end face 13 opposite the apex with the radiation source 5 and is coupled to the radiation-sensitive organ 6. Of course is the arrangement of the radiation source and the radiation-sensitive organ with Only schematically with respect to the end face or the end faces of the light guide body specified The parts mentioned can be placed in bores or recesses in the light guide body be embedded, so that the emitted or received radiation is fully utilized or as completely as possible.

The radiation source 5 and the radiation-sensitive organ 6 need not located in the immediate vicinity of the measuring point surface area 4 to be, but can be at the end of an elongated, rod-like section of the light guide body 1 are located. It is important, however, that the rod-like, cylindrical part of the light guide body adjoining, the measuring point surface area auiweisende part continuously connects, as shown in Figure 3b, or only with one gentle bend is applied, as Figure 3a illustrates. Light guide body for facilities According to the invention, cylindrical or frustoconical sections can also be used have, to which the surface parts with steadily decreasing radius of curvature Connect in direction to a vertex.

In Figure 4, a device is shown in which the light guide body 14 has the shape of a cavity, which in a material known or constant Refractive index existing vessel 15 is provided. The cavity 14 can be via a supply line 16 and a discharge 17 are inserted into the flow of a substance, which with regard to its refractive index or with regard to the mixing ratio of its components should be investigated. In the lower area of the vessel 15 this is outside with a light-absorbing layer 18 provided.

The cavity 14 filled with the substance to be examined, which with its upper opening of the radiation source 5 and the radiation-sensitive Organ 6 is facing with the measuring device 7 connected to it, corresponds in its Operation of the light guide body 12 of the embodiment according to Figure 3. -The in The embodiment shown in FIG. 5 differs from that according to FIG only in that the shape of the vessel 15 is adapted to the shape of the inner cavity 14 and that accordingly the light-absorbing layer 18 is also directly of the form of the cavity 14 corresponds.

Contains a fraction of its components in terms of fraction or mixing ratio If the substance to be examined has more than two mixture components, then that of the measuring device 7 no longer unambiguous, but corresponds to ii case of three Mismatch components of an infinite number of combinations, which in a certain wavelength of the light from the radiation source 5 to a certain strength of the light flux received at the radiation-sensitive organ 6 and thus lead to a certain electrical current which excites the measuring device 7 If, as shown in FIG. 6, the mixing ratio is plotted with respect to the components A and B on the one hand and with respect to components A and C on the other hand in one plane and assigns the current display of the measuring device 7 as the height to the individual points for the mixing ratio in question, there is a specific one for each Wavelength gives a characteristic area F1 and for a different wavelength For example, a characteristic area F2.

Obtained when using a certain wavelength of the radiation source 5 a certain display on the measuring device 7, this means the definition of a Contour line on the characteristic surface F1 or F2. If now from the radiation source 5 alternately once one wavelength and once another wavelength in the light guide body is sent out, a display is obtained on the measuring device 7, which in a timing diagram has approximately the form shown in FIG. this means that by measuring with two different wavelengths one can either follow one another or at the same time can determine that point of the contour lines according to Figure 6, which is assigned to the actual mixing ratio of the substance to be examined is.

It is the intersection of the contour lines of the characteristic Areas F1 and F2 in a plan view.

Instead of the concentration or the mixing ratio three components can with the same arrangement also the mixing ratio with respect to two components and additionally the temperature of one of two mixture components existing substance can be determined, as the temperature as well as a third mixture component the size of the refractive index influenced Figure 7 shows schematically a device, in which two radiation sources 5a ra and 5b are provided, which alternate to a Voltage source 19 are placed so that the light guide body 12 once with light from a first wave and then with light from a second Wavelength is applied. The measuring device 7 then supplies the diagrams shown in FIG reproduced sequence of display values, from which according to the above considerations Let the mixing ratios and / or the temperature be determined.

An alternating application of light to the light guide body 12 different wavelength can according to the embodiment of Figure 9 also through a filter disk 20 set in rotation by a motor with filter sectors 21a and 2Lb can be reached, which alternate in the radiation path between the radiation source 5 and the light guide body 12 reach.

As shown in FIGS. 10 to 12, however, a radiation source can also be used 5 can be used, which acts on the light guide body 12 with radiation, which contains several different wavelengths that occur simultaneously.

To derive two displays, each with different wavelengths In these cases, instead of a single, radiation-sensitive Organ two such radiation-sensitive organs 6a and 6b are provided. In the The embodiment according to FIG. 10 is, for example, photocells with respect to the wavelength of different responsiveness, for example around a germanium diode and a silicon diode.

In the embodiment according to FIG. 11, photocells are the same in each case Sensitivity selected, but different color filters are connected upstream in each case, so that in turn there is a different response with respect to the wavelengths of the individual organs sensitive to radiation. The embodiment according to FIG ii can also be modified in such a way that similar to FIG. 9 with respect to the Strutllurgsquelle explains, here the radiation-sensitive organ a rotating filter disc is connected upstream, so that on a single measuring instrument ment in chronological order two displays, each assigned to a wavelength value appear.

Finally, FIG. 12 shows an arrangement in which the radiation-sensitive Organs 6a and 6b of photosensitive resistors with different sensitivity maximum are formed.

Finally, there are some advantages of the devices according to the invention particularly pointed out. Because of the profiling of the explained with reference to FIG Surface of rod-like or disk-like or also rotationally symmetrical light guide bodies is achieved that lead to the weakening of the Liohtstromes from a radiation source the relationship to an organ that is rentable or sensitive to radiation decisive at the phase boundary in a very narrowly limited surface area are, in which all rays, which have the possibility at all, of the radiation source to be reflected to the radiation-sensitive organ, at least hit once and thus be used for the measurement. This gives you in each case a very clear display, a high sensitivity of the arrangement and a low one Susceptibility to malfunctions, for example, due to different immersion depths or because of inclination or the like.

The measurements can be made because of the simple shape of the light guide body and because of the possibility of moving towards the radiation source and the radiation-sensitive Setting up a longer section of fiber optic cable in between with extreme temperature and / or pressure conditions as well as in areas where there is a risk of explosion Environment, because of these properties, there are the inventive Installation is also possible with minimal technical effort for example to determine the state of steam in high pressure vessels using a simple rod feedthrough for the light guide body the only connection path to an environment with extreme Represents conditions.

Claims (10)

Claims y device for measuring the refractive index of liquids or gases, especially for determining the mixing ratio of several components of such Liquids or gases, characterized in that a radiation source (5) and a photosensitive member (6) each with end face areas (13) of a light guide (1 or 12 or 14) are coupled, which adjoins the end face areas Has surface parts (3) with a steadily decreasing radius of curvature merge into a measuring point surface area (4) of the light guide without at this measuring point surface area the radius of curvature is zero (edge or Tip) and that at the phase boundary in the measuring point surface area a substance with the refractive index to be determined and a substance with constant or known Breohzahl adjoin each other. 2. Device according to claim 1, characterized in that the light guide (1) from at least one in the vicinity of the measuring point surface area (4) corresponding to an asymptological or i'arabs tisohen curve, in particular correspondingly a hyperbola / or a chain line or an ellipse, curved light guide rod is formed, with the ends of which on the one hand the radiation source (5) and on the other hand the photosensitive member (6) are coupled, the apex of the bend being the Represents measuring point surface area (4). 3. Device according to claim 1, characterized in that the light guide from one at least in the vicinity of the measuring point surface area (4) with respect to its axial section according to an asymptotic curve, in particular correspond-or Parabola corresponding to a hyperbola / or chain line or Ellipse profiled rod or body of revolution (12 or 14) is formed, wherein the vertex of the rod or solid of revolution is the surface area of the measuring point (4) and an opposite end face (13) with both the radiation source (5) and is coupled to the photosensitive member (6). 4. Device according to one of claims t to 5, characterized in that that the light guide has the shape of one of the refractive indexes to be examined Fabric fillable cavity (14) has. 5. Device according to one of claims i to 3, characterized in that that the light guide (1 or 12) at least in the measuring point surface area (4) a room (8) is adjacent, in which the refractive index to be examined Fabric is fillable. 6. Device according to one of claims 1 to 5, characterized in that that in addition to the radiation source (5a) mentioned, a second radiation source (5b) is provided with a different emission maximum with respect to the wavelength and that the two radiation sources the light guide (12) alternately in time Apply sequence. 7. Device according to claim 6, characterized in that the radiation sources two alternately switchable emitters with different emission maximums are provided are (Figure 7). 8. Device according to claim 6, characterized in that the two Radiation sources are formed by a structural unit (5, 20, 21a, 21b) which has a Radiators generating radiation of several wavelengths as well as radiators that can be alternately connected upstream Contains color filters (Figure 9). 9. Device according to one of claims 1 to 5, characterized in that that the radiation source (5) emits radiation of several wavelengths and 'that in addition to said photosensitive organ (6a), another photosensitive one Organ (6b) is provided, which is different in terms of wavelength Has responsiveness. (Figures 10 to 12). 10. Device according to claim 9, characterized in that the different Responsiveness of the photosensitive organs by connecting different ones Color filter is generated (Figure 11).